Oil quality sensor and adapter for deep fryers

ABSTRACT

A system for measuring the state of degradation of cooking oil or fat includes at least one fryer pot; a conduit fluidly connected to the fryer pot for transporting cooking oil from the fryer pot and returning the cooking oil back to the fryer pot. A pump for re-circulating cooking oil to and from the fryer pot; and a sensor disposed in fluid communication with the conduit that measures an electrical property of the cooking oil as the cooking oil flows past the sensor and is returned to the at least one fryer pot is provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part application of U.S.application Ser. No. 12/215,307 filed on Jun. 26, 2008 now abandoned,which claims benefit under 35 U.S.C. §119(e) of U.S. ProvisionalApplication Ser. Nos. 60/937,513, filed on Jun. 28, 2007, and 60/995,527filed on Sep. 27, 2007, the contents of which are incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an oil quality sensor that is installed in afryer for the purpose of indicating when the cooking oil should bechanged for one or more fryer pots. This invention, more particularly,relates to oil quality sensor that measures an electrical property ofthe oil and is disposed in a filtration loop of a fryer that is externalto the one or more fryer pots.

2. Description of Related Art

During use, the oil in a fryer is degraded and loses its proper cookingcapacity. Specifically, the degradation is caused by oxidation, cyclictemperature increases and hydrolysis from released water. Impuritiesthat are generated during the frying process are collectively calledtotal polar materials (TPMs) or total polar compounds (TPCs). The TPMsare created during the deep-frying process as triglycerides break intofree fatty acids and lipid molecule residues. These substances arecharacterized by an increased polarity and dielectric constant comparedto the original triglycerides in the oil. Thus, an increased capacitancemeasurement of the cooking oil is indicative of an increased level ofTPMs in the cooking oil.

There are several methods for testing the quality of cooking oil. Simplemethods such as testing the taste, smell and color of the oil areexcessively subjective, inaccurate and too time consuming. Other methodstest the smoke point or viscosity of the oil. Again, while thesemeasurements are fairly simple, they are too dependant on factors suchas oil type and oil debris to be universally reliable.

Processes that include chemical or chromatographic methods are generallymore comprehensive and accurate than the simpler methods. For example,currently the most widely used test tests the fatty acids that arereleased from glycerines during the frying process. This test dependsstrongly on the moisture of the frying goods. Testing for polymerictriglycerides that are formed from frying triglycerides is often timeconsuming and expensive.

Accordingly, there is a need for an oil quality sensor that is able todetect the level of all deterioration products or TPMs for installationin an oil return line of a fryer that uses a capacitance sensor todetermine the change of dielectric constant of the cooking oil tounacceptable levels.

SUMMARY OF THE INVENTION

The present disclosure provides for a sensor disposed externally to adeep fryer that is able to indirectly measure the level of TPMs incooking oil by measuring the an electrical property of the cooking oil.

The present disclosure also provides for a capacitance sensor for a deepfryer pot that measures the capacitance of frying oil that is located ina conduit in fluid communication with the fryer pot.

The present disclosure also provides for a sensor for a deep fryer potthat is one of a capacitance sensor, a coaxial sensor or a resonantsensor that is dispose external to the fryer pot to measure anelectrical property of the cooking oil when such oil flows past thesensor.

The present disclosure further provides for a sensor that measures thecapacitance of the cooking oil in the return line of a fryer pot afterthe oil has been filtered.

The present disclosure also provides for a capacitance sensor that isdisposed in the oil return line of a deep fryer that is optimallypositioned to ensure that the flow of the oil cleans the sensor beforemeasurement of the capacitance of the cooking oil.

The present disclosure further provides for a sensor that measures thecapacitance of the oil and is disposed in a filtration loop between thefilter pan and the return valve to be returned to a plurality of fryerpots.

The present disclosure also provides for a capacitance sensor that is inthe return line of a plurality of fryer pots. The capacitance sensorrepeatedly measures the capacitance of the filtered oil during theentire return flow duration and obtains an average value of thecapacitance of the oil that is returned to each of the plurality offryer pots.

The present disclosure provides for an adapter that houses a capacitancesensor for the measure of a dielectric constant. The adapter isinstalled between two portions of a return pipe of a fryer pot to enablefiltered oil to flow past sensor for measurement before returning to thefryer pot. An indication is provided when the dielectric constant of thecooking oil has exceeded an unacceptable level.

A system for measuring the state of degradation of cooking oil or fatincludes at least one fryer pot; a conduit fluidly connected to thefryer pot for transporting cooking oil from the fryer pot and returningthe cooking oil back to the fryer pot. A means for re-circulatingcooking oil to and from the fryer pot; and a sensor disposed in fluidcommunication with the conduit that measures an electrical property ofthe cooking oil as the cooking oil flows past the sensor and is returnedto the at least one fryer pot is provided.

A system for measuring the state of degradation of cooking oil in a deepfryer includes at least one fryer pot and a conduit fluidly connected tothe at least one fryer pot for carrying cooking oil from the at leastone fryer pot through a filtration unit back to the at least one fryerpot. A sensor disposed in fluid communication with the conduit formeasuring a dielectric constant of the cooking oil as the cooking oil ispumped between the at least one fryer pot and through the filtrationunit is provided. A controller and measurement electronics in electricalcommunication with the sensor that computes the dielectric constant ofthe cooking oil for communication to a display or an alarm are provided.

A device for installation in a deep fryer for measuring the state ofdegradation of cooking oil includes a sensor disposed on a supportsurface and in fluid communication with a conduit containing cooking oilthat measures an electrical property of the cooking oil. The device alsoincludes a connector for connection to a controller and measurementelectronics in electrical communication with the sensor that computesthe dielectric constant of the cooking oil that flows past the sensor.

BRIEF DESCRIPTION OF THE DRAWING

Other and further benefits, advantages and features of the presentdisclosure will be understood by reference to the followingspecification in conjunction with the accompanying drawings, in whichlike reference characters denote like elements of structure.

FIG. 1 illustrates an exemplary fryer housing a sensor of the presentinvention;

FIG. 2 illustrates an oil quality sensor according to the presentinvention incorporated into the return pipe of the filtration loop ofthe fryer of FIG. 1;

FIG. 3 illustrates an oil quality sensor according to the presentinvention incorporated into the drain pipe of the filtration loop of thefryer of FIG. 1;

FIG. 4 illustrates an oil quality sensor according to the presentinvention incorporated into the filter pan of the filtration loop of thefryer of FIG. 1;

FIG. 5 illustrates an oil quality sensor according to the presentinvention incorporated into the filter pan of the filtration loop havinga single pipe associated with the fryer pot;

FIG. 6 illustrates a partial cross-section view of the sensor of FIG. 2along line 6-6; and

FIG. 7 illustrates a further view partial cross-section view of thesensor of FIG. 6.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 1, an illustration of an exemplary fryer is shown, andgenerally represented by reference numeral 10. Deep fryer 10 has ahousing 5, a pair of fryer pots 15 and a pair of filter pans 40. Each ofthe pair of filter pans 40 contains a pre-filtering medium, such as asieve 35 that is used to remove large particles from the used cookingoil. Alternatively, both fryer pots 15 could share a common filter andreturn system. While fryer 10 is shown as only having two fryer pots 15,there could be as many as twelve fryer pots depending upon the needs ofthe food service professional. Fryer 10 also has a controller 20 formonitoring and maintaining overall operation the fryer 10. Deep fryerhousing 5, also has a display panel 31 that displays variousmeasurements of deep fryer and accepts input for programming ofcontroller 20. The present application is not limited to cooking oil,thus fat or shortening could also be used in the present application.

Referring to FIG. 2, filtration loop 50 of fryer 10 incorporates asensor and is shown, and referenced using reference numeral 100. Sensor100 is shown in the return line 70 of filtration loop 50; however,sensor 100 preferably is disposed along filtration loop 50 external tofryer 10, in accordance with the present disclosure. Thus, sensor 100 isdisposed in filtration loop 50 external to fryer pot 15 independent ofthe configuration of filtration loop 50, as shown in FIGS. 3 through 5.Further, sensor 100 is capable of measuring an electrical property ofcooking oil 75 such, as the dielectric constant, of oil. Sensor 100 ispreferably one of a capacitance sensor, an open ended coaxial sensor, aconductivity or a resonant type sensor.

Referring again to FIG. 2, filtration loop 50 has a drain line 55, and apre-filtration sieve 35, and a fine filtration pad 30. Cooking oil 75 isreturned through plumbing 70 by pump 65. Prior to reaching pump 65,sensor 100 in flow of returning filtered cooking oil 75 is able tosample the an electrical property as oil 75 is being returned to fryerpot 15. A filtration loop that services multiple fryer pots would have agate valve 42 and common drain plumbing 43 disposed upstream of pan 40to collect used oil 75 from multiple fryer pots 15. Similarly, a returnline splitter 82 and a valve 83 would direct filtered oil to specificfryer pots 15.

Referring to FIG. 3, sensor 100 is disposed in drain pipe 55 offiltration loop 50. In this embodiment, an electrical property ofcooking oil 75 is repeatedly sampled as oil 75 is drained from fryer pot15. A filtration loop 50 that services multiple fryer pots 15 would havea gate valve 42 and common drain plumbing 43 disposed upstream of pan 40to collect used oil 75 from multiple fryer pots. Similarly, a returnline splitter 82 and a valve 83 would direct filtered oil to specificfryer pots 15.

Referring to FIGS. 2, 3, 6 and 7, sensor 100 is contained withinT-shaped adapter 105 that extends within housing 5 generally beneathfryer pot 15. T-shaped adapter 105 is connected in return-line ofcooking oil of pipe 70. T-shaped adapter 105 is preferably connectedbetween two portions of return pipe 70, upstream portion 71 anddownstream portion 72, in a mating relationship via mating threadsdisposed on interconnecting portions thereof. Oil sensor 100 extendswithin adapter 105 and is positioned to lie in the stream of flow of oil75, such that the flow of oil 75 from upstream portion 71, throughadapter 105 to downstream portion 72 is uninterrupted. Additionally, theflow of oil 75 is coincident with longitudinal axis of upstream portion70, downstream portion 72 and adapter 105 installed between portions 71and 72. Oil sensor 100 extends within and is protected by adapter 105.

Referring to FIG. 4, sensor 100 is disposed in filtration loop 50, infilter pan 40. In this configuration, the dielectric constant offiltered cooking oil is sampled in pan 40 prior to passing throughfiltration pad 30 and returning to fryer pot 15.

Referring to FIG. 5, filtration loop 50 configuration also has sensor100 disposed to sample an electrical property of oil external to fryerpot 15. In this configuration, sensor 100 is disposed in filtration loop50; however, there is only a single conduit 80 that is in fluidcommunication with fryer pot 15. In this configuration valve 81 is athree-way valve that is controlled by controller 20 to direct cookingoil through pipe 55 during a draining cycle and to open to permitfiltered oil to be pumped back and return to fryer pot via pipe 80. Inthis configuration, sensor 100 could have been disposed within pipe 55,or 70 external to fryer pot 15. In this configuration, pump 65 canservice multiple fryer pots 15.

Oil sensor 100 is located in an adapter 105 in the filtration loop offryer pot 15 as shown in FIGS. 2 and 3. Sensor 100 is located to measureand continuously sample an electrical property of cooking oil 75 beforeit re-enters fryer pot 15, independent of its location external to fryerpot 15. When the triglycerides of filtered cooking oil 75 break intofatty acids and lipid molecules during the heating and cooking cyclesthe polarity of oil 75 increases. The accumulation of polar materialslowers the insulating properties of cooking oil and elevates thedielectric constant of cooking oil 75 to higher values. This increasedpolarity correlates with an increased dielectric constant of oil 75.Thus, sensor 100 is able to measure the change of the TPM values bymeasuring the dielectric constant of cooking oil 75 as pump 65 returnsoil to fryer pot 15. When sensor 100 detects an unacceptable level ofTPMs an indication is provided to an operator to change the oil. Thus,sensor 100 ensures that oil 75 is not wasted by being prematurelychanged or overused thereby tainting food and harming consumers.

Oil sensor 100 is operatively connected to measurement electronics 44and controller 20 of fryer 10 via plugs 110. Electronics 44 andcontroller 20 enable periodic measurements made by sensor 100 forcalculation of TPM values are averaged before oil 75 returns to fryerpot 15.

Referring to FIGS. 6 and 7, sensor 100 is disposed on a support surface115 that extends within adapter 105. Sensor 100, in one embodiment as acapacitor 111, is made from highly conductive wires 101 that arepreferably printed onto support surface 115. Sensor 100 is configuredsuch that a constant space is between separate highly conductive wires101 thereby forming a capacitor 111. Highly conductive wires 101 arepreferably made of gold, although other materials having highlyconductive properties could also be used. Capacitor 111 is preferablyprinted on support surface 115 that is made from a ceramic material.Capacitor 111 has two ends 102 that are each connected to leads 103 thatare also printed on support surface 115. Leads 103 are connected at oneend to capacitor 101 and at the other connector end to plugs 110 viacable 104 for connection to measurement electronics 44 and controller20. Thus, the non-conductive quality of ceramic support surface 115provides electrical insulation between adjacent wires of capacitor 111and leads 103. When sensor 100 is not part of an adapter 105, sensor 10extends within filtration unit as shown in FIGS. 4 and 5.

Prior to measurements, sensor 100 achieves operational temperatures bybeing in the flow of quickly moving cooking oil 75 caused by pumpreturning oil to fryer pot 15. The quickly flowing cooking oil 75 alsoacts as a scrubber to clean sensor front 106 and sensor back 107 as itpasses thereby to be returned to fryer pot 15. Sensor 100 must be cleanto provide accurate measurements of oil capacitance and an indication ofwhen oil must be changed. Sensor 100 must be properly positioned suchthat sensor front 106 and sensor back 107 are cleaned. Thus, sensor 100and support surface 115 on which sensor 100 is disposed are, optimallypositioned and angled to take advantage of the approaching flow of oil75 that is flowing through or in-line with both portions 71 and 72 ofreturn pipe 70. The placement angle 130 of approximately 20° to 50°relative to the direction of oil flow shown by centerline orlongitudinal axis of pipe 70 having portions 71 and 72 and adapter 105ensures that the oncoming filtered cooking oil will clean sensor front106. Sensor 100 is cleaned by the impulse of the flow on the highpressure side in front of sensor 100 and the vortex generation of thelow pressure side down-stream of sensor 100. Thus, flow of oil contactssensor front 106 at an angle of from 20° to 50°. Were sensor 100 notproperly angled, insufficient cleaning of the sensor front 106 andsensor back 107 would occur and the sensor measurements would becompromised and inaccurate. Additionally, sensor 100 must be clean toenhance the useful life of sensor 100.

Support surface 115 also includes a temperature sensor 120 proximatesensor 100. Temperature sensor 120 is preferably formed as an electricalresistor. Temperature sensor 120 is connected by electrical leads 103,as sensor 100, for connection to controller 20 and measurementelectronics 44. Controller 20 continuously receives signals viaamplifier and A/D converter from capacitance sensor 100 and temperaturesensor 120, for measurements of oil capacitance and oil temperature.Thus, the dielectric constant of the oil is constantly being measured atvarious temperatures as oil flows through adapter 105 by sensor 100 atit returns to fryer pot 15. Measurements are provided to display toindicate the actual degree of decomposition of the oil 75, so thatoperator may know when oil should be changed.

Sensor 100 repeatedly samples TPM in cooking filtered cooking oil 75,these data are sent to measurement electronics 44 and controller 20 viacable 104 and connector 110. The measurements are averaged over theduration of the return of filtered cooking oil 75 to fryer pots 15.Thus, the calculated averaged value of the TPMs can be calculated andcompared to known accurate values to detect the dielectric constant ofthe cooking oil. Controller 20 is capable of storing acceptabledielectric values of clean cooking oil for comparison to the measuredvalues. Should the dielectric constant of filtered cooking oil 75 exceeda predetermined threshold, an indicator, such as an audible or visiblealarm, is engaged. Additionally, display on display panel 31 showsmeasurements.

Optionally, visible alarms can be color-coded to indicate a level ofmeasured dielectric acceptability. For example, a color such as greenindicates good quality oil, amber would indicate that oil needsreplacement shortly and red would indicate that the oil is of poorquality and needs to be immediately changed.

The present invention having been thus described with particularreference to the preferred forms thereof, it will be obvious thatvarious changes and modifications may be made therein without departingfrom the spirit and scope of the present invention as defined in theappended claims.

We claim:
 1. A system for measuring the state of degradation of cookingoils or fats in a deep fryer comprising: at least one fryer pot; aconduit fluidly connected to said at least one fryer pot fortransporting cooking oil from said at least one fryer pot and returningthe cooking oil back to said at least one fryer pot; a means forre-circulating said cooking oil to and from said fryer pot; and a sensorexternal to said at least on fryer pot and disposed in fluidcommunication with said conduit to measure an electrical property thatis indicative of total polar materials of said cooking oil as thecooking oil flows past said sensor and is returned to said at least onefryer pot; wherein said conduit comprises a drain pipe that transportsoil from said at least one fryer pot and a return pipe that returns oilto said at least one fryer pot, wherein said return pipe or said drainpipe comprises two portions and said sensor is disposed in an adapterinstalled between said two portions, and wherein said adapter has twoopposite ends wherein one of said two ends is connected to one of saidtwo portions and the other of said two ends is connected to the other ofsaid two portions.
 2. The system of claim 1, wherein said sensor is acapacitance sensor, a coaxial sensor, a conductivity sensor or aresonant sensor.
 3. The system of claim 1, further comprising afiltration unit, wherein said filtration unit is disposed in-line withsaid conduit.
 4. The system of claim 1, wherein said conduit comprises asingle pipe that drains oil from said at least one fryer pot and returnsoil to said at least one fryer pot via said single pipe.
 5. The systemof claim 1, further comprising a display or an alarm in electricalcommunication with said sensor for indicating the degradation of cookingoil to a user.
 6. The system of claim 1, wherein said sensor is disposedin said adapter that is connected to said return pipe or to said drainpipe.
 7. The system of claim 1, further comprising a staged alarmaccording to different values of degradation.
 8. The system of claim 3,wherein said sensor is disposed in said filtration unit.
 9. The systemof claim 1, wherein said means for re-circulating is a pump.
 10. Thesystem of claim 9, wherein said pump is disposed either before or aftersaid sensor and said at least one fryer pot to pump oil past said sensorto said at least one fryer pot.
 11. The system of claim 1, wherein saidsensor is disposed on a support surface contained within said adapter.12. The system of claim 6, further comprising a connector in electricalcommunication with said sensor that extends from said adapter forconnection to a controller and measurement electronics.
 13. A system formeasuring the state of degradation of cooking oil in a deep fryercomprising: at least one fryer pot; a conduit fluidly connected to saidat least one fryer pot for carrying cooking oil from said at least onefryer pot through a filtration unit back to said at least one fryer pot;a sensor disposed between said filtration unit and said at least onefryer pot for measuring filtered cooking oil; said sensor being in fluidcommunication with said conduit for measuring a dielectric constant thatis indicative of total polar materials of the filtered cooking oil, asthe cooking oil is pumped between said at least one fryer pot andthrough said filtration unit; and a controller and measurementelectronics in electrical communication with said sensor that computesthe dielectric constant of the cooking oil for communication to adisplay or an alarm; wherein said conduit comprises a drain pipe thattransports oil from said at least one fryer pot and a return pipe thatreturns oil to said at least one fryer pot, wherein said return pipe orsaid drain pipe comprises two portions and said sensor is disposed in anadapter installed between said two portions, and wherein said adapterhas two opposite ends wherein one of said two ends is connected to oneof said two portions and the other of said two ends is connected to theother of said two portions.
 14. The system of claim 13, wherein saidsensor is disposed in an adapter that is connected to said conduit. 15.The system of claim 13, further comprising a pump, wherein said pump isdisposed between said sensor and said at least one fryer pot to pump oilfrom said filtration unit to said fryer pot.
 16. The system of claim 13,wherein said conduit comprises a single pipe that drains oil from saidat least one fryer pot and returns oil to said at least one fryer potvia said single pipe.
 17. A device for installation in a deep fryer formeasuring the state of degradation of cooking oil in a fryer potcomprising: a sensor disposed in a conduit with flowing cooking oil tomeasure and sample an electrical property of the cooking oil that isindicative of total polar materials of the cooking oil; and a controllerand measurement electronics operatively connected to said sensor toprovide measurements and to calculate and average total polar materialvalues during cooking oil return to the fryer pot; wherein said conduitcomprises a drain pipe that transports oil from said at least one fryerpot and a return pipe that returns oil to said at least one fryer pot,wherein said return pipe or said drain pipe comprises two portions andsaid sensor is disposed in an adapter installed between said twoportions, and wherein said adapter has two opposite ends wherein one ofsaid two ends is connected to one of said two portions and the other ofsaid two ends is connected to the other of said two portions.
 18. Thedevice of claim 17, wherein said adapter comprising a hollow tube and aconnector perpendicular to said hollow tube, wherein said sensor isdisposed in said hollow tube.
 19. The device of claim 17, wherein saidsensor is one of a capacitance sensor, a coaxial sensor, a conductivesensor or a resonant sensor.
 20. The device of claim 18, wherein saidhollow tube comprises two threaded surfaces disposed on opposite endsthereof for connection to said conduit.
 21. The device of claim 17,wherein said conduit is one of a pipe or a filter pan.
 22. A system formeasuring the state of degradation of cooking oils or fats in a deepfryer comprising: a plurality of fryer pots, a filtration loopcomprising a filter pan and drain plumbing that collects used cookingoil from said plurality of fryer pots and a return conduit that returnsfiltered cooking oil to each of said plurality of fryer pots; a meansfor re-circulating said cooking oil through said filtration loop to andfrom said plurality of fryer pots; and a sensor external to saidplurality of fryer pots and disposed in fluid communication with saidcooking oil to measure an electrical property that is indicative oftotal polar materials of said cooking oil as the cooking oil flows pastsaid sensor and is returned to said plurality of fryer pots; whereinsaid drain plumbing comprises at least one drain pipe associated witheach said fryer pots, wherein said drain pipe transports oil from saidfryer pot, and said return conduit that returns oil to each of saidplurality of fryer pots, wherein said return conduit or said drain pipecomprises two portions and said sensor is disposed in an adapter has twoopposite ends wherein one of said two ends is connected to one of saidtwo portions and the other of said two ends is connected to the other ofsaid two portions.
 23. A system for measuring the state of degradationof cooking oils or fats in a deep fryer comprising: at least one fryerpot; a conduit fluidly connected to said at least one fryer pot fortransporting cooking oil from said at least one fryer pot and returningthe cooking oil back to said at least one fryer pot; a means forre-circulating said cooking oil to and from said fryer pot; a sensorexternal to said at least one fryer pot and disposed in fluidcommunication with said conduit to measure an electrical property thatis indicative of total polar materials of said cooking oil as thecooking oil flows past said sensor and through said means forre-circulating; wherein said conduit comprises a drain pipe thattransports oil from said at least one fryer pot and a return pipe thatreturns oil to said at least one fryer pot, wherein said return pipe orsaid drain pipe comprises two portions and said sensor is disposed in anadapter installed between said two portions, and wherein said adapterhas two opposite ends wherein one of said two ends is connected to oneof said two portions and the other of said two ends is connected to theother of said two portions.